Midrash, Hebrew, "interpretation", is a type of Jewish
literature concerned with the interpretation of biblical texts. Perhaps
the earliest attempts in midrash concerned the Passover, and Haggadah which
includes the interpretation of Deuteronomy 26:5-8. The aggadic
midrashim seeks to derive a moral principle or theological concept from
scriptures, while the halakhic midrashim
aim to explain the complete meaning of a biblical law. The rabbis formulated
various rules to deduce hidden or new meaning, and midrash was produced
from the tannaaitic period until the 12th
century AD. The best known example is the collection Midrash Rabbah
on the Pentateuch and five megillot. Tanhuma
contains discussions on the weekly portion of the Torah
which is read on the synagogue. The pesiktot contain midrashim for
special Sabbaths and festivals. Collections of midrashic teachings include
Derekh Eretz Rabbati, Derekh Eretz Zuta, and Tanna de-ve-Elyahu.
Avot de-Rabbi Natan is an expansion of the tractate Avot.
And Pirke de-Rabbi Eliezer contains stories about biblical events.
From the 12th century various anthologies of midrashim were compiled which
drew from earlier sources; examples include the Yalkut Shimeoni,
and the Midrash de-Gadol. A.G.H.

Source:

Bowker, John, The Oxford Dictionary of World Religions,
New York, Oxford University Press, 1997, p. 640